In previous section we have observed the interaction loop. All its parts define the effectiveness of interaction, but the most important one is the visible, external part of machine — it’s input and output devices.
This is most important, because we can not modify ourselves (make our eyes better, change our perception capacity and so on — we will discuss human possibilities and features later) , and we have only limited possibility to modify hidden logic of the user and machine.
And this part is called user interface — the set of input and output devices and the way, how they behave, i.e. receive user actions and send machine’s responses and feedback.
Actually, user interfaces appear when there is a distinct difference between manipulated object and manipulators — and some hidden connecting logic between them. That is why the spoon doesn’t have user interface — because we manipulate the spoon itself. That is why first mechanisms several centuries ago also didn’t have the UIs — the user observed and manipulated the navigational sextant or ancient windmill parts directly. But that is why the first button of door bell, the earliest harpsichord musical keyboard and gun trigger were the user interfaces indeed, because the button and the doorbell, the key and the string, the trigger and the firing pin have been separated.
Of course, typically “user interface” term is used only for graphic representations on the computer screen, but that is too narrow statement. Examples of user interfaces in wide sense are:
- Computer monitor and text processor displayed on it and keyboard with mouse for input.
- Automobile wheel, dashboard and sensor panel of multimedia system
- Yoke, thrust levers, buttons, indicators and multifunctional displays of airplane cockpit console
- Handles and even firebox of steam locomotive
Later we will move to more traditional “user interface” statement, related to graphic user interfaces and command line interfaces, but it is very important to keep in mind, that these ones are only important parts of general computer UIs.
How to select, set up and use these devices in interaction lifetime dynamics and make it most effective — this is the primary task of UX design.
But before diving deep, we should look closer at machines, humans and other components of interaction loop.